Freshwater flow dominated by monsoon rains rather than glacier run-off.
Reposted from naturenews (nature.com)
Richard A. Lovett
Although global warming is expected to shrink glaciers in the Himalayas and other high mountains in Central Asia, the declining ice will have less overall impact on the region’s water supplies than previously believed, a study concludes.
It’s an important finding, says Richard Armstrong, a climatologist at the US National Snow and Ice Data Center in Boulder, Colorado, who notes that the Intergovernmental Panel on Climate Change had previously predicted dire restrictions on water supplies in Asia. “There clearly were some misunderstandings,” he says.
The researchers behind the latest study began by calculating the importance of meltwater in the overall hydrology of five rivers: the Indus, the Ganges and the Brahmaputra in India, Pakistan and Bangladesh, and the Yellow River and the Yangtze in China1. The authors found that meltwater is most important to the Indus, with a contribution roughly 1.5 times that from lowland rains. In the Brahmaputra, meltwater flow is equivalent to only one-quarter of the volume supplied by lowland rainfall, and, in the other rivers, it forms no more than one-tenth of the input.
Furthermore, the study found that in the Indus and Ganges basins, glacial ice contributes only about 40% of the total meltwater, with the rest coming from seasonal snows. In the other three rivers its contribution is even lower.
High and dry?
That’s important, says Walter Immerzeel, a hydrologist at FutureWater in Wageningen, The Netherlands, and lead author of the study1, because Asian rivers are fed by three sources: rain, snow melt and melting glaciers.
The first two are driven by current weather patterns, because rains fall either as water or as snow that will later melt. The last is a carry-over from the build-up of glaciers in prior centuries. As the glaciers shrink, their contribution will also decline until the glaciers have either melted entirely, or stabilized at smaller sizes.
The interesting thing about Indus is that it flows through the Karakoram, where the glaciers are in fact advancing…
Point of sphaerica, what makes you think they got the rest of AGW right. This is just one more piece of evidence that AGW proponents don’t understand how to do science.
Is the AGW
Hmm, lots of misunderstandings to correct here too.
Sam, Kargel’s comment is entirely consistent with the results of the study.
The impact “less than thought” is for the whole area considered, including Yellow river etc. Kargel referred to the Indus, which the study shows as being severely affected. The study also says the supportable population for the whole region will be 4.5% below the population now. And I can’t believe we’ll see a massive relocation of people from the Indus and Brahmaputra to China.
CodeTech, RHS, Hannibal B, LarryC, Dennis Nikols, Rick Espen, Nylo, Jimbo: what’s rather important about glacial meltwater for these Asian rivers is that it spreads the flow around the seasons. Without glaciers to act as reservoirs, most will go through in the period just following the monsoon. A shrunk glacier will tend to mean, I believe, less annual variation in volume, this becoming particularly obvious once it hits zero in the summer melt.
P. Solar: If you read the whole article you’ll see it considers changes in precipitation too. That’s how it arrives at increased flows in the Chinese rivers.
Rocky Road: Depends whether you adopt a sensible test of whether a prediction is right. Mostly the debate is around what will tend to happen in the future, and it will take maybe 100 years to validate the claims. The few that have been so specific as to be testable already would have been dismissed as rash by most climate scientists. That’s what’s so hard about the whole issue: we have to adopt policy long before the science can possibly be certain. The policy currently adopted by the world assumes the science is more wrong than right, and there’s certainly no evidence for that.
Sam says:
June 11, 2010 at 8:10 am
Seems like this would be good news for policymakers, right? Less worry about how people will get freshwater. But look at this quote:
The findings are important for policy-makers, says Jeffrey Kargel, a glaciologist at the University of Arizona in Tucson. “This paper adds to mounting evidence that the Indus Basin [between India and Pakistan] is particularly vulnerable to climate change,” says Kargel. “This is a matter that obviously concerns India and Pakistan very much.”
Great. No matter what the evidence shows, it is mounting evidence for worrying about climate change.
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Yeah, notice how they neglected to point out that the opposite of “global warming” that is, global cooling is much worse. If the earth goes into a cooling mode and the glaciers stop melting and INCREASE in size, then the rivers lose not only the extra glacial melt water cused by the shrinlage in glacier size, but also the part of the annual snow melt that is now turning into ice. Depending on the annual precipitation amounts this could be a real bummer.
Warm is good, cold is bad is proved again.
Juraj V. says:
June 11, 2010 at 8:41 am
Can you imagine that these people design airplanes for example?
“The wing will be 30 meters wide – or maybe just 13?”
Once one of those university creature boasted that most of the scientists (in universities and governmental institutions) are leftist, trying to claim intellectual supremacy. Now I understand why such people gather in public sector: with their junk work, they would not survive in a private sector for a single month.
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Boy is that the truth. I had a new boss who had been a government scientist, they fired him within three months and it took two people six months to clean up the mess he made.
Anon says:
June 11, 2010 at 12:40 pm
I’m just discovering your blog and am confused…I thought you were against Nature as a publication. Why are you using it as evidence for your opinion now?
Are they redeemed when the science they present fits your expectation?
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Articles from anywhere that are interesting turn up at this site. Unlike REALCLIMATE, Anthony does not try to slant his website and only muzzles inappropriate language, ad hominem etc.
Have you bothered to read the comments???
Dammed if you do, dammed if you don’t:
(Found while looking for something better)
“For this reason we have examined the alternatives to the alternatives; conventional energy options such as fossil fuels (including heavy oil), nuclear power, and hydroelectricity. In our report “China’s Renewable Energy,” it is clear what a nation with a strong central government can accomplish. The Three Gorges hydroelectric complex will have a capacity of 17.5 gigawatts, a staggering amount of energy – the single massive Three Gorges installation will output more than 50% of the entire output of every one of India’s current hydroelectric power stations combined! But in democratic India, projects of such magnitude take time, as they probably should. Not every gorge should be dammed.”
Sorry, for the Socialist slant of the excerpt. I didn’t write it.
I’ve spent a great deal of time in the Mekong region including the Delta area of Hau Giang and An Giang – as well as in the Himalaya – and as I wrote somewhere a few days ago, the seasonal monsoons (and dry seasons) have 100 times more impact on Mekong Delta flooding than anything coming from the upper Mekong including Himalayan melt.
And I think this is verified by observation and speaking with my wife and her family, who have lived within 10 to 30 meters of the Mekong for several generations. Not only has there been no significant or unusual flooding of the Mekong Delta plain in my own observations of the last 15 years, but there hasn’t been anything unusual for at least the last 40 or 50 years or more, according to my spouse and her family.
This story – about Himalayan melt causing increased Mekong Delta flooding – was so utterly preposterous that I could not believe anyone was stupid enough to put a byline on it.
In all of Southeast Asia, anyone with eyeballs can observe that it is the natural and normal monsoon season that causes flooding. And even a complete dope knows that the Mekong Delta is a natural flood plain, and has been for millenia.
Gail Combs says:
June 11, 2010 at 7:25 pm
This is a misunderstanding of how glaciers work. The top of the mountain, because temperature decreases with altitude, is always below freezing. Precipitation drops there (the snow caps seen on mountains), increasing the mass and weight and packing it into ice. The force of gravity on this mass first packs the snow into ice, and then drives the ice downward — the slow advance of the glacier like a frozen river. Eventually, the slow flowing glacial ice gets below the altitude where temperatures are above freezing. At that altitude the glacier starts to melt, producing the end of the glacier, and water.
From this mechanic, you can see several things. One is that a glacier could, in theory, produce runoff year round, although if winter temperatures at sea level are below freezing, this wouldn’t happen.
Also, one main factor in glacier productivity is moisture and precipitation at the summit, adding more ice mass to the top (source) of the glacier and in that way increasing the eventual runoff, and potentially lengthening the glacier merely by adding more mass, making it harder to melt as quickly.
One thing a change in temperatures will do is to raise the altitude at which the melting occurs (i.e. shrink the glacier), and potentially destroy the glacier if that altitude rises too far.
Alternately, a simple shortening of the glacier could cause it to terminate at a point where the water collects in a pool or lake, instead of continuing down the mountain, thus depriving the adjacent basin of the water (which would instead evaporate).
I’d encourage you to do some research on glaciers before forming opinions on anything. They’re actually quite fascinating.
Good grief, it now appears the trolls have the ability to clone themselves, e.g. “sphaerica”, and now its clone “Point of Fact”.
Population growth in India over the next 40 years is be expected to increase the population by about 30%, China somewhat less.
Every one of those people will be beyond the extra 60 million the the region can currently support…… suggesting a problem that will actually affect one third of a billion people.
Problems with population growth and consequential stress on available water supplies are not unknown elsewhere. The answer lies in better water management. As has been pointed out, it is when the glaciers start growing again, thus locking up water, that they will have something to worry about. There again, adaptation is the key, not whining and blaming the C02 bogeyman.
Gail Combs says:
June 11, 2010 at 7:51 pm
Anon says:
June 11, 2010 at 12:40 pm
Neither site, in my experience, does much in the way of deleting comments, although I have heard of people from both camps complain of having valid comments deleted, or even being permanently blocked. To assume that any one site is “good” and the other is “bad,” and to say it out loud, is I think very unfair, and demonstrates irrational bias.
The content of the comments is another issue, however. Again, both sites get argumentative (which is sort of the fun part, isn’t it?), and there are certain people that go over the top into ad hominem attacks and such — the general approach is to label anyone who disagrees with the local consensus as a troll. This happens everywhere, and has happened here, to me, quite frequently and recently.
And on both sides, there are people that refuse to listen, or that treat the debate as a game instead of an argument. That is, they are 100% invested in making their own point, to the extent of shutting their ears and eyes and refusing to even admit to any truth in any aspect of the other side’s arguments. This eventually leads to people saying “you won’t listen, so forget you” and the conversation first turns angry, and then ends. And again, this happens at both sites.
The point I mean to make here is that your perspective is that “here” is good and “there” is bad, because you agree with the opinions presented “here.” These are “your people.” But people “there” think the same of “here.”
A true skeptic has an open mind, and isn’t clouded either by preconceptions, or more importantly by an emotional investment in one side of an argument.
Pot. Kettle. Mirror.
Everyone should take responsibility for and monitor their own behavior in how they participate in this debate. Show respect. The sites themselves are generally pretty good about being fair about the comments. The people who comment are the culprits.
Derek B says:
June 11, 2010 at 5:31 pm
Good points! Melting or growing I’m just waiting for the evidence that manmade C02 induced warming has caused any retreat. You might find the following interesting.
Are all Himalayan glaciers melting?
http://news.bbc.co.uk/2/hi/8387737.stm
http://www.sciencemag.org/cgi/content/full/326/5955/924
Himalayan glaciers ‘melting’ due as much to soot and dust as CO2
http://www.nasa.gov/topics/earth/features/himalayan-soot.html
http://www.nasa.gov/topics/earth/features/himalayan-warming.html
http://www.atmos-chem-phys-discuss.net/9/26593/2009/acpd-9-26593-2009.html
Swiss glaciers melted faster in the 1940’s than today
http://www.ethlife.ethz.ch/archive_articles/091214_gletscherschwund_su/index_EN
Some glaciers are growing
http://www.ihatethemedia.com/12-more-glaciers-that-havent-heard-the-news-about-global-warming
http://www.climategate.com/12-more-glaciers-that-haven%e2%80%99t-heard-the-news-about-global-warming
“This paper adds to mounting evidence that the Indus Basin [between India and Pakistan] is particularly vulnerable to climate change,” says Kargel.
The Indus Basin lies right smack dab in the middle of Pakistan. Its *source* is in Tibet, but it flows northwest through the Himalayas and into the Karakorams, where it exits and flows south. The biggest contributors to its volume are snowmelt from the Karakorams and the Hindu Kush to the north, the Spin Ghars to the west, and the annual monsoons — *not* melting glaciers.
Garry: June 12, 2010 at 2:56 am
In all of Southeast Asia, anyone with eyeballs can observe that it is the natural and normal monsoon season that causes flooding. And even a complete dope knows that the Mekong Delta is a natural flood plain, and has been for millenia.
I flew in the Delta for a year, and it’s the perfect example of a flood plain. The terrain is perfectly flat, average elevation — excluding the Seven Sisters Mountains — is less than six feet above sea level, and the water table is generally about two feet below the surface.
Someone correct me if I’m wrong. It seems to me that the existence of a glacier is a minor factor in the water flow. A certain amount of precipitation falls over the area and that water eventually makes it to the sea with some evaporation along the way. While a glacier might delay the flow and/or change exactly when it flows, it doesn’t have much impact on the total amount (although any delay probably leads to more evaporation).
Hence, it seems to me that a series of dams should be able to provide the same delaying effect. Once again man can control his own destiny … the one thing AGW proponents ignore time and again.
check my dutch blog about this topic with data from Dan Alford
R. Armstrong, D. Alford, and A. Racoviteanu, A preliminary assessment of the role of glaciers in the hydrologic regime of the Nepal Himalaya, Geophysical Research Abstracts, Vol. 11, EGU2009-10794, 2009
http://www.vkblog.nl/bericht/293177/Himalaya%3A_Gletsjersmelt_geen_invloed_op_waterhuishouding
Pat you have it all wrong on ground water levels being supported by trees! Especially on the sides of mountains. trees will however hold down topsoil and prevent erosion which could lead to poorer growing conditions for future plants. Usually though you only need any kind of wild uncultivated plant life to prevent erosion and of course trees keep cold weather warmer and hot weather cooler because of there modulating effect on the near surface air.
Bruce Cobb says:
June 12, 2010 at 5:52 am
You misunderstand what glaciers are, and how they work. Refer to my previous post on the matter on this page, or look for other sources, but glaciers aren’t as simple as big blocks of ice that don’t melt when they’re growing and do melt when they’re shrinking. They are nothing like either of those two.
Jimbo says:
June 12, 2010 at 7:42 am
Himalayan glaciers ‘melting’ due as much to soot and dust as CO2
And who are the largest polluters of soot in the region?
Answer: India, Pakistan, China.
While on the subject of Glaciers.
Glaciers’ wane not all down to humans
Is it all down to man-made global warming? Not according to a recent study, which finds that about half of the glacier loss in the Swiss Alps is due to natural climate variability1 — a result likely to be true for glaciers around the world.
http://www.nature.com/news/2010/100604/full/465677a.html
sphaerica says:
June 12, 2010 at 4:10 pm
You misunderstand what glaciers are, and how they work. Refer to my previous post on the matter…
Your knowledge of glaciers and how they work is quite fascinating. Perhaps you could do a post on them explaining in detail how, given the same amount of available moisture a glacier can be growing and still provide the same amount, or more of available melt water. We’re aware they do provide melt water whether growing or shrinking. The issue is the amount.
Indian civilisation has suffered in the past when the sister river of the Indus, the Sarasvati river, failed completely and is now mostly a dry river bed. The Sarasvati was possibly fed by remnant ice from the last ice age and features in the Rig Veda. This perhaps illustrates the fragility of such water sources over time; with or without supposed AGW.
It just hit me that the argument of glacial melt being vital to the water supply is rubbish…
If the folks who are hyping a Vegas-style glacial david copperfield act got their way and the glaciers stopped melting and remained permanently in their current state, their contribution to river flow would cease completely, leaving only the annual snow melt that falls on top of the glaciers and melts each year. If the glaciers begin growing, then water that deposits or falls on the glaciers and would have become snow melt is staying in place as new glacial ice, therby reducing the flow further than when the glaciers are shrinking.
So if it’s water supply that’s wanted, the best shot is when the glaciers are melting. It will decrease when they stop melting and further decrease when they start growing again. AHHH!!! Run for the hills (to fetch a pail of snow).